The field of the invention is dry powder inhalers.
Inhalers are used to deliver drugs into a patient's lungs. Typically, an inhaler contains or provides a mixture of drug particles and air or propellant gas. The mixture is delivered by the patient inhaling from a mouthpiece on the inhaler with the air or propellant gas carrying the drug particles into the patient's lungs.
In dry powder inhalers, the drug particles, in the form of a fine dry powder, are entrained into an airflow and inhaled by the patient. Dry powder inhalers are often used for treating bronchial asthma. However, drugs delivered via a dry powder inhaler can also be used to treat many conditions, including conditions unrelated to the lung, via the systemic absorption of the drug into the bloodstream, through the lung.
Treatment of certain conditions, such as asthma, requires a frequent dosing regimen, with the patient taking e.g., two doses each day. Accordingly, a dry powder inhaler able to deliver a large number of doses, such as 60, 90, or even 120 doses, before the inhaler needs to be refilled or replaced, would be advantageous. Some proposed dry powder inhalers achieve the goal of providing large numbers of doses by individually metering out one dose at a time from a bulk powder storage compartment within the inhaler. However, with these designs, it is difficult or impossible to seal water vapor out of the bulk powder. Consequently, powder caking or clumping or particle size growth may result, affecting how well the powder is disbursed in air. This tends to decrease the dose actually provided to the patient and/or lead to inconsistent doses.
To avoid this disadvantage while still providing a large number of doses, dry powder inhalers using a dose tape or strip have been used. The flexible strip has spaced apart pockets each containing a dose of pharmaceutical powder. By winding the strip into a coil, a large number of doses may be contained within a compact inhaler. The doses are sequentially released by incrementally peeling apart top and bottom layers of the strip or tape. While these types of dose strip or tape inhalers can provide a large number of doses, while also better maintaining the physical stability of the powder by sealing out water vapor, disadvantages remain. For example, it can be difficult to avoid double dosing with these types of inhalers, i.e., opening two or more of the pockets or containers on the dose tape before inhaling, causing the patient to inhale a much larger dose than intended. In addition, since known dose tape inhalers unseal each dose of the tape via mechanical actuation by the patient, a dose can be released or unsealed from the tape and exposed to water vapor in the environment unless the dose is promptly inhaled. In addition, certain known dose strip inhalers have relatively complex mechanical designs, adding to manufacturing complexity and cost.
Accordingly, there is a need for an improved dry powder dose tape inhaler.